NAME:………………………………………………………..………INDEX NO:………………

DATE:……………………

SIGN:……………………..

232/2

PHYSICS

PAPER 2

(THEORY)

OCT/NOV - 2013

TIME: 2 HOURS

KCSE ONLINE EXAMINATION – FORM THREE 2013

Kenya Certificate of Secondary Education (K.C.S.E)

232/2

PHYSICS

PAPER 2

(THEORY)

OCT/NOV - 2013

TIME: 2 HOURS

INSTRUCTIONS TO CANDIDATES

1. Write your name and index number in the spaces provided at the top of this page.

2. Sign and write the date of examination in the spaces provided above.

3. This paper consists of TWO sections: A and B

4. Answer ALL the questions in the sections A and B in the spaces provided.

5. ALL working MUST be clearly shown.

6. Non-programmable silent electronic calculators and KNEC mathematical tables may be used.

FOR EXAMINERS USE ONLY.

SECTION / QUESTIONS / MAXIMUM SCORE / CANDIDATE’S SCORE
A / 1 – 14 / 25
B / 15 / 08
16 / 14
17 / 09
18 / 11
19 / 12
Total Score / 80

This paper consists of 10 printed pages.

Candidates should check the question paper to ensure that all pages are printed as indicated and that no questions are missing.

SECTION A (25 MARKS)

  1. A ray immerges from a mirror S at an angle of 300 to the mirror as shown in the figure below. On the same diagram complete the ray path to show its incident path to mirror Q and state the angle of incidence. (2marks)

Ray

300

Q S

800

R

  1. A gold leaf electroscope is positively charged, state what happens when a neutral metal is brought near the cap. (1 mark)
  1. Figure 1 shows four bar magnets placed close together.

N

S

SNNS

S

NFigure 1

In figure 1 sketch the magnetic field pattern between the four magnets. (1mark)

  1. A current of 2.0Ais passed through a resistor of 2Ω for1hr calculate the heat energy dissipated in the resistor (3 Marks)
  1. a) Define electrical resistivity. (1mark)

b) Conductivity of an electric conductor depends on thickness .List other two factors that affect the conductivity of an electric conductor. (2marks)

  1. A man makes a loud sound and hears the echo of the sound after 1.5 seconds. If the speed of sound in air is 330ms-1, calculate the distance between the man and the wall causing the echo. (3Marks)
  1. The figure below shows image formed by concave mirror, sketch the rays to show the position of the object if the mirror has a magnification. (3 Marks)

C f I

  1. Figure 2 represents the section of a wire between the opposite poles of two bar magnets.

Figure 2

On the same diagram indicate the direction of the force on the wire. (1mark)

  1. The figure below is a layout of a simple periscope. Construct rays to show how the image of the object O is formed (2 marks)
  1. Figure below shows a diagram of a simple dc motor.

Name the parts labeled A and B.(1 Mark)

A ______

B ______

  1. Differentiate between electromotive force and potential difference of a cell. (1 Mark)
  1. State one advantage of having prism in periscope instead of plane mirrors.(1Mark)
  1. With the aid of a well labeled diagram, illustrate how a solar eclipse occurs. (3 Marks)

SECTION B (55 marks)

  1. a) The figure shows an electrical circuit including three switches S1, S2 and S3 ,and three Identical bulbs L1, L2 and L3 .A potential difference is applied across X and Y.

S2 L2

S1 L1

XY

L3 S3

(i). Other than L1, state the lamp that will light when S1 and S2 are closed(1Mark)

(ii) State how the brightness of L1, in (i) above compares with its brightness when all the switches are closed? (1Mark)

(iii) Explain the observation in (ii) above (1Mark)

b) Figure below shows a cell in series with 3Ω resistor and a switch. A high resistance voltmeter is connected across the cell.

3Ω

The voltmeter reads 1.5V with the switch open and 1.2V with the switch closed.

(i).State the electromotive force of the cell. (1Mark)

(ii) Determine the current through 3Ω resistor when the switch is closed. (2Marks)

(iii) Determine the internal resistance of the cell. (2Marks)

  1. (a) Define absolute refractive index. (1Mark)

(b) A ray of light travels from air into medium 1 and 2 as shown.

Air400

M1 240

N1

N2

M2 260

Air

N3

Calculate;

(i) Refractive index of medium 1(3Marks)

(ii) Critical angle of medium 1(3Marks)

(iii) The refractive index of medium 2 relative to medium 1.(3Marks)

(c) State two conditions necessary for total internal reflection to occur.(2Marks)

(d) Paraffin has greater refractive index than that of water, comment onthe velocities of light in paraffin and in water. (2Marks)

  1. (a) State the motor rule. (1 Mark)

(b )The diagram below shows an electric bell

(i)Describe how the electric bell works. (4 Marks)

(ii) State what would happen if the armature is made of steel. (1 mark)

(ii)Give one adjustment that should be made to the system to make it operate effectively at a lower voltage battery. (1 mark)

c) State two applications of electromagnets. (2 Marks)

  1. A) (i) State the law of electrostatics. (1 mark)

(iii)What is the SI unit of charge? (1 mark)

(iii) Is it safe to stay in a car during a lightning storm? Explain.(2Marks)

b) The figurebelowshows a circuit consisting of a 6V cell, a 200 resistor, a 20 F capacitor and a switch S1 connected in series. Another 200 resistor and switch S2 are connected in parallel to the capacitor.

(i) On axes provided sketch graphs showing how the voltage VR across resistor R1 and the voltage VC across the capacitor vary with time when switch S1 is closed and switch S2 remains open. (2Marks)

(ii) What is the maximum voltage across the capacitor when fully charged? (1Mark)

(iii) Determine the maximum charge on the capacitor. (2Marks)

c) Lightning conductors are installed on tall buildings to protect them from damage by lightning. The lightning conductor does this in two ways. Explain (2Marks)

  1. (a) A student attached a mass to a spring such that when it oscillates it taps on water surface in a wide shallow tank as in figure below.

The student measured time for 20 oscillations and found that the mass takes 36 seconds.

Determine:

(i)The periodic time of the mass (2Marks)

(ii)The frequency of the waves produced on the water surface (1Mark)

(iii)The speed of the waves if the students counted four ripples between the mass and end B of the tank. (3Marks)

(b)State two factors that would increase the speed of sound in air (2Marks)

(c)The figure below shows a displacement-time graph of a wave. The velocity of the wave is 100m/s.

Determine;

(i)Amplitude, (1Mark)

(ii)Wavelengthof the wave.(3Marks)

1